Dual effect of tannic acid on the preservation and ultrastructure of phosphatidyl choline vesicles
The use of tannic acid has been proposed to improve the preservation of phospholipids in tissues. We investigated the effects of tannic acid on the preservation of small unilamellar vesicles, prepared from sonicated aqueous suspensions of phospholipids.
With cryo-electron microscopy it is demonstrated that small unilamellar vesicles are formed after sonication of the phospholipid suspensions. Fixation of vesicles without tannic acid results in extraction of the phospholipids during dehydration and embedding. Fixation of vesicles containing phosphatidyl choline with tannic acid, with or without glutaraldehyde, results in a fast (within a second) aggregation of the vesicles and the resulting sediment can be dehydrated and embedded when a postfixation in osmium tetroxide is carried out. Small unilamellar vesicles fixed in this way are retrieved in thin sections as multilamellar vesicles with a periodicity of about 5 nm for dimyristoylphosphatidyl choline and about 6 nm for dioleoylphosphatidyl choline.
By using 14C-phosphatidyl choline it was also demonstrated that tannic acid prevents to a large extend the extraction of phosphatidyl choline during fixation, dehydration and embedding. This dual effect of tannic acid on phosphatidyl choline, aggregation and fixation, should be considered when using tannic acid in tissue preparation.
Key wordstannic acid phosphatidyl choline fixation aggregation
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- 7.Ikeda H: An ultrastructural analysis of the inclusion body in the type II pneumocyte processed by rapid freezing followed by freeze — substitution — An autoradiographic study. J Electron Microsc 34: 398–410, 1985Google Scholar
- 9.Schrijvers AHGJ, Frederik PM, Heijnen VVTh, Reneman RS: Increased number of multilamellar extrusions after prolonged ischemia and reperfusion in rabbit myocardium (abstract). J Moll Cell Cardiol 20 (Suppl. V): S31, 1988Google Scholar
- 10.Mizuhira V, Futaesaku Y: On the new approach of tannic acid and digitonine to the biological fixatives. Proc Electron Microsc Soc Am 29: 494–495, 1971Google Scholar
- 15.Frederik PM, Stuart MCA, Bomans PHH, Busing WM: Phospholipid, nature’s own slide and coverslip for cryo-electron microscopy. J Microsc (Oxford), in pressGoogle Scholar
- 16.Frederik PM, Stuart MCA, Schrijvers AHGJ, Bomans PHH: Thin film formation and the imaging of phospholipid by cryo-electron microscopy. In: The science of biological specimen preparation, SEM, O’Hara AMF, in pressGoogle Scholar
- 17.Duzgunes N, Hong K, Baldwin PA, Beutz J, Nir S, Papa-hadjopoulos D: Fusion of phospholipid vesicles induced by divalent cations and protons — Modulation by phase transitions, free fatty acids, monovalent cations, and polyamines. In: Sowers AE (ed.). Cell fusion. Plenum Press, New York, 1987, pp 241–267Google Scholar